Citizen scientists are an underrated source of observations on medical conditions. They frequently offer researchers a head start in the hunt for biomarkers (see, for example, the tentative identification of volatile indicators of early Parkinson's disease: go.nature.com/wggoss).
The precision and high-throughput capability of analytical technology drives most advances in clinical diagnostics ( et al. Nature 502, 317–320; 2013). Analytical science and its subdiscipline metabolomics (the study of chemical fingerprints left by cellular processes) are also crucial for guiding clinical decisions (see go.nature.com/l8pcde). These tools are set to be valuable for investigating and tapping into citizen scientists' previously unreported medical phenomena.